Czech dark lager is a hard style to pin down. It’s not quite a German Dunkle and it’s not quite an English Porter. It’s somewhere in between. I’m going to brew one up and we’re going to talk about grain mills. So as it’s become a custom now for brewing these Czech beers, the base malt is Bohemian floor malted Pilsner malt.
Some Biscuit malt or Victory malt, as Martin included in his recipe adds some unfermentable sugars to retain even more body. Finally, a quarter-pound of acidulated malt is added for pH correction or control. Saaz hops are more traditional for a Czech Pale Lager.
We also have the same smooth bittering found in most Plzen-inspired beers, thanks to a water adjustment to soften things up. Finally, don't get too distracted by this as a "dark" lager (or a "black beer," as it is sometimes described in the original Czech) - it's dark-ish, but think in terms of dark flavor than dark color.
Usually Czech lagers are 10 or 12 degrees, which equates to 4-5% abv. Fact #9 Old time Czech beer drinkers sometimes like more foam than beer. This was a common way to check the quality of a beer. You experience the sweet taste of the foam and the bitter flavor of the beer.